A green, efficient and recyclable Fe+3@K10 catalyst for the synthesis of bioactive pyrazolo[3,4-b]pyridin-6(7H)-ones under "on water" conditions

Pd–Ce/ZIF-8 Nanocomposite for Catalytic Extraction of Sinomenine from Sinomenium acutum

Sinomenine is a naturally occurring alkaloid and commonly used as one of the bioactive drug components in rheumatoid arthritis (RA) treatment in the clinic. Varying supported palladium-based catalysts have been synthesized and examined as heterogeneous catalysts for catalytic extraction of sinomenine from Sinomenium acutum. Among various examined supported catalysts, Pd–Ce/ZIF-8 (zeolitic imidazolate framework-8) demonstrates promising catalytic activity in the extraction reaction with an improved yield of 2.15% under optimized conditions. The catalyst composite can be recovered by centrifuging, and reused. A total of three catalyst recycling processes were performed with constant activity. The catalyst Pd–Ce/ZIF-8 has a particle size range of 2–12 nm and a total Pd–Ce loading amount of 5.1 wt% (ZIF-8).

Benzimidazolyl-pyrazolo[3,4-b]pyridinones, Selective Inhibitors of MOLT-4 Leukemia Cell Growth and Sea Urchin Embryo Spiculogenesis: Target Quest

1,3-Substituted pyrazolo[3,4-b]pyridinones 11-18 were synthesized by a three-component condensation of Meldrum's acid with aryl aldehydes and 1,3-substituted 5-aminopyrazoles. Their biological activity was evaluated using the in vivo phenotypic sea urchin embryo assay and the in vitro cytotoxicity screen against human cancer cell lines. In the sea urchin embryo model, 1-benzimidazolyl-pyrazolo[3,4-b]pyridinones 11 caused inhibition of hatching and spiculogenesis at sub-micromolar concentrations. These compounds also selectively and potently inhibited growth of the MOLT-4 leukemia cell line. Subsequent structure-activity relationship studies determined the benzimidazolyl fragment as an essential pharmacophore for both effects. We applied numerous techniques for target identification. A preliminary QSAR target identification search did not result in tangible leads. Attempts to prepare a relevant photoaffinity probe that retained potency in both assays were not successful. Compounds 11 were further characterized for their activity in a wild-type versus Notch-mutant leukemia cell lines, and in in vitro panels of kinases and matrix metalloproteinases. Using a series of diverse modulators of spiculogenesis as standards, we excluded multiple signaling networks including Notch, Wnt/β-catenin, receptor tyrosine kinases (VEGF/VEGFR, FGF/FGFR), PI3K, and Raf-MEK-ERK as possible targets of 11. On the other hand, matrix metalloproteinase-9/hatching enzyme was identified as one potential target.

An Efficient One-Pot, Four-Component Synthesis of Pyrazolo[3,4-b]pyridines Catalyzed by Tetrapropylammonium Bromide (TPAB) in Water

A novel and one-pot pseudo-four-component reaction between a series of arylglyoxals, malononitrile, 3-methyl-1-phenyl-1H-pyrazol-5-amine, and acetone in the presence of tetrapropylammonium bromide (TPAB) has been developed to synthesize a series of new substituted pyrazolo[3,4-b]pyridines, using water as an environmentally friendly solvent, in high to excellent yields.

"On-Water" Facile Synthesis of Novel Pyrazolo[3,4-b]pyridinones Possessing Anti-influenza Virus Activity

A facile and versatile "on-water" protocol for the synthesis of pyrazolo[3,4-b]pyridinones was developed by the unprecedented construction of two rings and five new bonds in one-pot. It was proved that water was an important promoter of the reaction and PEG2000 was found to improve the reaction in terms of yield. 32 Derivatives were newly synthesized and most of them were prepared in an hour. The scope and limitation indicated that electron withdrawing groups substituted on synthons, substituted benzoyl acetonitriles or aryl aldehydes, were helpful to construct the pyrazolo[3,4-b]pyridinones. The reaction media PEG2000/H₂O was successfully recycled and reused at least 5 times without any obvious decrease in yield. The anti-influenza activities of the derivatives were evaluated and the screening results highlighted two derivatives, which exhibited strong inhibitory activity against H5N1 pseudovirus. These positive bioassay results implied that the library of potential anti-influenza virus agent candidates could be rapidly prepared in an eco-friendly manner, and provided a new insight into drug discovery for medicinal chemists.

[γ-Fe2O3@HAp-SO3H] an Efficient Nanocatalyst for the Synthesis of Highly Functionalised 2-thioxopyrido[2,3-d]Pyrimidines

HAp(hydroxyapatite)-encapsulated-γ-Fe2O3 supported sulfonic acid nanoparticles were used for the preparation of two series of 2-thioxopyrido[2,3-d]pyrimidines. In the first series, 2-thioxopyrido[2,3-d]pyrimidines were synthesised from 3-(6-amino-1,2,3,4-tetrahydro-4-oxo-2-thioxopyrimidin-5-yl)-3-oxopropanenitrile and arylaldehydes in the presence of [γ-Fe2O3@HAp-SO3H] as a nanocatalyst, in high yields (84–96%). In the second series, [γ-Fe2O3@HAp-SO3H] was used to catalyse the reaction of 6-amino-2-(alkylthio)-pyrimidine-4,6(1H,5H)-dione, 1,3-diethyl-2-thioxodihydropyrimidine-4,6(1H,5H)-dione and various arylaldehydes to prepare 2-thioxo-2,3,7,10-tetrahydropyrido[2,3-d:5,6-d']dipyrimidine-4,6 (1H,5H)-diones in excellent yields (93–98%).

Rapid and Efficient Synthesis of Spiro-Oxindoles using Fe3+-Montmorillonite under Ultrasonic Irradiation

A simple and efficient one-pot three-component approach was devised for the synthesis of spiro-oxindoles through the reaction of isatin derivatives, malononitrile and 1,3-dicarbonyl compounds in the presence of modified montmorillonite (Fe3+-mont.) under ultrasonic irradiation. The reaction furnished the desired products in excellent yields (85–95%) and short reaction times (2–7 min).